Just back from Cuba (birding) to a closed university etc. I would agree with Jacques that X. guepinii is the best match (super material), but I have not studied this complex for decennia so feel a bit rusty. It is still a possibility that both scotica and my own friesii should be lumped with guepinii.

bw

Thomas

I would like to thank both excellent interlocutors for their contributions. I am very happy.
Have a nice day - Przemek

Hallo all,
I read a new article about this species: Hsieh H-M, Ju Y-M, Lechat C, Fournier J, Huart D. New ecological, morphological, cultural and molecular phylogenetic insights into Xylaria guepini (Xylariaceae) Ascomycete.org. 2022;14:177–184.
I very much regret that the authors lacked scientific inquisitiveness and did not ask me for part of my collection for comparative analysis. :-( Especially since, when comparing the morphology of both collections, due to significant differences, especially (though not only) in the aspect of conidiogeny, it should be assumed that they are different species of the Xylaria genus.
I am fully willing to cooperate in further research on this species (unfortunately I do not have the ability to conduct genetic research myself),
best regards, Przemek